HU208584B - Multifocus double refraction lens system - Google Patents

Abstract

A multifocal birefringent lens system is described together with applications of the lens system such as ophthalmic lenses (including those of the intraocular, contact and spectacle type) and optical instruments and devices including photographic cameras, telescopes, microscopes, copiers, spectrographic instruments, etc.

Description

The present invention relates to a multi-focal, non-achromatic or achromatic multipart optical lens system, more particularly to a lens system in which at least one of the lens portions has a dual refractive index.

Dual refractive lenses have long been known. GB 231848 (UK) discloses a dual refractive lens for use in a polarizer. Dual refractive lenses produce two directions of light polarized at different angles, so a single aperture or isotropic lens is used to eliminate the two polarized light beams when only one directional polarized light is desired. US-A-2317809 discloses a thin convex dual refractive lens which is adhered to a thin convex isotropic lens on the convex side. This system acts as a lens that serves as a positive magnifier for one linear polarization state light and as a zero optical magnification parallel plate for the other linear polarization state light. The lens system is built into the viewfinder for photographic purposes. In GB 865 361 (UK), a prismatic dual refractive lens is combined with an isotropic top lens so that the two magnifications of the lens combination differ equally from the magnification at the radiation receiving surface. The lens system is embedded in an optical device used for eye examination. The device separates the two images formed by the o- and e-rays so that two images of different sharpness can be seen side by side during the eye examination. (Of the two types of light waves, o-rays are called ordinary light waves, and e-rays are extraordinary light waves.) U.S. Patent No. 3,210,10448 refers to a system of thin convex / thin convex lenses in which the lenses are of the same dual light are. In the system, one of the two dual-refractive lenses can be replaced by a flat-surface isotropic lens. The system is integrated with a headlamp optical component such as a prism and a polarizer in a spectrometer. U.S. Pat. No. 3,423,238 also discloses a planar coffee / planar convex dual refractive lens system for generating phase shifting of incident polarized light.

The resulting interference images can be used in a spectrometer.

Since the dual refractive lens has one magnification for one plane of linear polarization and another magnification for another orthogonal plane of polarization, means for rotating the plane of polarization can be used to select one of the two magnifications when the incident light is linearly polarized. U.S. Patent No. 3,410,624 uses an electro-optic control device (Kerr cell) with dual refractive lenses and prisms. This patent discloses that a system m comprising a lens and an electro-optical cell can produce a focal point of 2 ^m . A similar system consisting of n electro-optic cells and n dual-refractive lenses is described in French Patent No. 1552,198. U.S. Patent No. 3,520,592; and "Multiple Imagery with Birefringent Lenses" by Eng et al., Vol. 8, Volume 10, No. 2117-2120. (October 1969) discloses a focusing optical system using one or more dual-refractive lenses, each of which is combined with a control member for the polarizing plane of light. U.S. Pat. No. 35,636,332 discloses a numerical optical focal length controller in which a series of successive stages consisting of a Kerr cell and a progressive twin-refractive lens are immersed in a common electrolytic vessel. The lenses are configured so that the temperature dependence of the refractive index of the electrolyte is compensated. U.S. Patent No. 3,555,510 discloses the use of two dual refractive lenses per Kerr cell in a system similar to the system described in U.S. Patent 3,563,632 above. Osipov, Journal of Binary Polarizing Lenses, Optical Technology, Volume 40, Issue 5, pp. 277-279. (May 1973) describes a dual polarizing lens having a dual refractive thin convex / thin coffee lens system. This lens system may be combined with an isotropic lens to produce a parallel reference beam and a focused signal beam. The light beams are orthogonally polarized for use in laser systems. U.S. Patent 3,758,201 discloses a thin convex / thin convex dual refractive dual lens combined with an isotropically variable magnification lens system. This system is used for eye examination. U.S. Patent No. 3,990,798 discloses a thin convex / thin convex dual-light refractive dual lens, which can be used as an eyepiece or lens of a microscope to produce images of objects in different object planes in a single image plane. Thin Convex / Thin Convex Double Lenses are also described in U.S. Patent No. 4,566,662, which is made of a double-refractive material. This patent describes a dual focus system in which images of objects at different distances show the same magnifications. U.S. Pat. No. 4,575,849 discloses thin convex / thin convex dual refractive lenses for use as a phase sheet in combination with an optical filter polarizer.

It follows from the foregoing that dual-refractive lenses are primarily thin-convex / thin-plane coffee systems2

HU 208 584 Β. Such a system is combined, for example, with Osipov's solution - an isotropic lens in order to produce a parallel beam of polarized light. A combination of prismatic dual-refractive and prismatic isotropic lenses is used in GB-A-865 361 (UK) for the purpose of producing eye-to-eye images of two objects side by side. Several patents further suggest lens assemblies or lens systems, each of which has a control means and a dual-refractive lens for adjusting the position of the polarizing plane, so that the lens system can have a variable focal length.

In the patents listed above, inorganic crystals such as quartz and chelate are mentioned as the material of the dual refractive lenses. The dual refractive properties of certain organic polymers may also be present. For example, 4384107; 4,393,194; 4,933,196; 4,333,132; 4,446,305; 4,461,886; 4,461,887; 4503 248; 4520189; 4521588; 4525413; 4575547; U.S. Patent Nos. 4,608,429 and 4,628,125 disclose polymers that exhibit high dual refractive properties and mimic the optical properties of uniaxial crystals. Such dual refractive polymers are proposed for use with isotropic layers in multilayer light transmission and polarizing devices.

The fact that double-refractive polymers, for example, are suitable for the testing of stresses, has long been known. The whole area of photo-elasticity and voltage analysis with polarized light is based on this phenomenon. It is also known that stretching a polymer beyond its elastic limit can irreversibly produce a double refractive property in the polymer. This is mentioned, for example, in U.S. Patent No. 3,522,985.

This property of multi-focal ophthalmic lenses and especially contact lenses is known, for example, from 3794414; 4210391; 4340283; 4,338,005, 4,637,697; 4,641,934; U.S. Patent Nos. 4,642,112 and 4,655,565. A common feature of these lenses is that the optical materials used to make them are isotropic. Multiple magnification at the same time, as described, is achieved by making the lenses with appropriate geometric parameters.

The prior art devices with dual refractive lenses did not allow independent selection of the surface curvature of the lenses and did not afford the degree of design freedom that is indispensable for such a task.

U.S. Patent No. 3,990,791 to White discloses a bifocal device that is mounted in a microscope to combine images of two separate objects in a single image plane. The bifocal device consists of a thin convex coffee and a thin convex lens portion. The two lens portions are glued along their complementary surfaces, since both surfaces have the same radius of curvature Rj.

As shown in equation 2 above, the following two magnifications of the bifocal device are obtained:

p _ (tte -%) p _ ( ⁿ e ~ Bp)

RR where n _{0 is} the optical refractive index of the normal light beam, n _e is the refractive index of the extraordinary light beam, and R is the radius of curvature of the lens.

From these two equations, it can be seen that the two magnifications cannot be chosen completely independently of each other, moreover, the radius of curvature R of the complementary lenses is functionally related to the magnification values P _x and P _y .

From this line of reasoning, it becomes clear that the surface curvature of the lenses cannot be selected independently of their associated focus and magnification values.

In the case where only one of the two lens parts of the lens system is double-refractive, the result is the following magnification values:

where n is the optical refractive index of the isotropic lens portion, n _{0 is} the optical refractive index of the regular ray, and n _e is the refractive index of the extraordinary ray, R is the radius of curvature of the lens.

From the above pair of equations, it appears that for a dual-refractive lens system, there is a relationship between the curvature radius R of the surfaces and the magnification values P _x , P _y . Accordingly, with respect to the lens system consisting of the dual-refractive lens portions, the above reasoning can be applied to the dual-refractive lens portion and the isotropic lens portion.

U.S. Patent No. 3,758,201 to MacNeille discloses a thin refractive lens system consisting of a thin cone and a thin convex lens, which is assembled with an adjustable magnification isotropic lens.

All geometric parameters of the MacNeille lens system are determined by the preselected diopter value and the raw material used to make the lens. As a result, the MacNeille lens system does not have any degree of design freedom.

U.S. Patent No. 2,317,809, to Sauer, discloses a bifocal lens system consisting of a thin coffee and a thin convex lens, similar to White and MacNeille. In the case where the bifocal lens component has a smaller optical refractive index (e.g., n ,,) as the second lens portion optical refractive index (e.g., n), the bifocal lens component has the following magnification:

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It is understood that the foregoing applies to the realization of the Sauer, White and MacNeille patents.

Summarizing the solutions known so far, each solution has the feature that the descriptions show only lens systems where the resulting magnification values are not independent of one another and where the magnification or magnifications are a function of the surface curvature of the lens portions.

It is a primary object of the present invention to provide a multi-focus lens system, such as two-focus, three-focus, four-focus, etc., non-achromatic or achromatic, with two refractive lenses, where at least two focal values can be independently selected.

Another object of the present invention is to provide a multi-focus, non-achromatic or achromatic, dual-refractive lens system that minimizes the amount of unwanted, unwanted focus or magnification.

It is a further object of the present invention to provide a non-achromatic or achromatic multi-focal dual-refractive lens system that exhibits superior freedom of choice in image sharpness, color or chromatic properties, and magnification relative to other known types of multi-focal lens systems.

It is yet another object of the present invention to provide a non-achromatic or achromatic dual-refractive lens system consisting wholly or partly of polymers of optical quality.

It is another object of the present invention to combine a non-achromatic or achromatic dual refractive lens system with one or more light polarizing devices and, optionally, one or more polarizing filters, to enable selection of magnifications or combinations of magnifications from a plurality of usable magnifications.

It is a further object of the present invention to provide a multi-focal, non-achromatic or achromatic, dual-refractive lens system in which at least one lens surface is independent of the physical parameters of the material used to manufacture the lens parts and the preselected focuses.

It is an object of the present invention to provide a dual-light refractive lens system that exhibits the desired degree of chromatic aberration in at least one of the preselected focuses.

It is also an object of the present invention to provide ophthalmic lenses, more particularly spectacle lenses, contact lenses and intraocular lenses, based on the non-achromatic or achromatic dual-refractive lens system of the invention.

OBJECTS OF THE INVENTION The present invention includes optical devices comprising dual-refractive lens systems of the invention, such as ophthalmic diagnostic devices, cameras, binoculars and binoculars, microscopes, copiers, optical instruments, spectrographs, and the like. creation.

The present invention relates to a multi-focus dual refractive lens system, comprising at least two lens portions, wherein the first lens portion is adjacent to a second refractive lens and the second lens portion, the second lens portion being combined with the first dual refractive lens or and a double refractive lens. In the case of a multi-focus lens system where the second lens portion is isotropic, two magnifications are obtained. Where the second lens portion is dual-refractive, four dioptric values are obtained.

The idea of the invention is that at least two of the four resulting magnifications in the arrangement of the two dual-refractive lenses, and both magnifications in the dual-refractive and isotropic lens system, can be preselected.

In the lens system of the present invention, the curvature of any surface of the first or second lens portion can be determined independently of any preselected magnification values (or diopter values) and preselected focus values.

The arrangement of the present invention is such that the curves of the adjacent surfaces of the two lens portions form a complementary pair.

According to a preferred object, the multi-focal non-achromatic dual light refraction lens system of the present invention, the lens system comprising a lens axis and comprising at least two lens parts, wherein:

the first lens portion being a dual refractive anisotropic medium lens having an optical axis perpendicular to the geometric axis of the lens portion and having refractive properties for each of the two light waves incident on the anisotropic medium, i.e. are

the second lens portion being disposed relative to the first lens portion and having the optical axis of the second lens portion different from the geometric axis of the first lens portion and having refractive properties with respect to both light waves, i.e., ordinary and extraordinary light waves; wherein the radius of curvature of the adjacent surface of the second lens portion adjacent to the first lens portion and the radius of curvature of the adjacent surface portion of the first lens portion adjacent to the second lens portion are complementary (complementary to each other);

In the lens system of the present invention, the optical axis of the second dual-refractive lens portion has a direction other than the optical axis of the first lens portion; or the optical refractive index of the second lens portion for two types of light waves, such as normal and extraordinary light waves, is different from the optical refractive index of the first lens portion for normal and extraordinary light waves4

HU 208 584 Β from the lake; or the refractive index of normal light waves of the second lens portion is equal to the refractive index of normal light waves of the first lens portion, but the refractive index of extra light waves of the second lens portion is different from that of the first lens portion; or the second lens portion has a refractive index of the same as the first lens refractive index, but in this case the second lens has a normal refractive index other than the first double refractive index of the lens configured so that for the light rays incident parallel to the lens axis, the lens system simultaneously has at least two focuses, each located at a predetermined point of the lens system axis, at a positive or negative focal length, and that the first lens portion or second lens portion or the value of at least one of the radii of curvature is independent of said two focuses.

A further feature of the lens system of the invention is that it has at least one first lens portion or a second lens portion that transmits extraordinary rays in a direction perpendicular to the optical axis of the first lens portion or second lens portion in the path of the light wave.

According to one of the criteria, one or more of the double-refractive lens portions are made of a double-refractive polymer material.

In another aspect, the second lens portion comprises at least one double-refractive lens portion or at least one isotropic lens portion.

The lens system comprises a polarizing means, wherein at least one polarizing filter, or only one or two pieces of double-light refraction lens, is disposed on the side of the dual-refractive lens in the direction of incident light.

In another embodiment of the multi-focus dual-refractive lens system of the present invention having at least one focus achromatic or having at least one degree of chromatic aberration, the lens system comprising a lens axis; where

the first lens portion being a double refractive lens having an optical axis perpendicular to the geometric axis of the lens portion and having a refractive property of both light waves incident on the anisotropic medium, i.e., normal and extraordinary light waves;

- a second lens portion disposed along the first lens portion, the optical portion of the lens portion having a different direction from the geometric axis of the first portion portion; which part of the lens acts as a refractive element for both light waves, that is, normal and extraordinary light waves; and the second lens portion is a double refractive or isotropic lens. The lens system of the present invention is configured such that the optical axis of the second dual-refractive lens portion is different from the optical axis of the first lens portion; or the optical refractive index of the second lens portion for the two types of light waves as normal and extraordinary light waves is different from the optical refractive index of the first lens portion for the two types of light waves, i.e. normal and extraordinary light waves, the refractive index of ordinary lens part, but in this case the refractive index of extraordinary light wave of the second lens is different from the first refractive index of first part of the lens, then the refractive index of the second lens portion for normal light waves is different from the first dual refractive lens for normal light wavelength refractive index, the lens system is further configured such that for the rays of light incident parallel to the lens axis, the lens system simultaneously has at least two focuses, each located at a predetermined point of the lens system axis, at least two focal lengths the focal length of one is essentially the same with respect to two focused wavelengths of different wavelengths.

A lens system having at least one focus having a chromatic aberration or a certain degree of chromatic aberration is further characterized by having at least one first lens portion or a second lens portion that transmits extraordinary rays perpendicular to the optical axis of the first lens portion or second lens portion.

The second lens portion has a dual refractive property that is substantially the same for two different wavelengths.

The lens system of the present invention is characterized in that the second lens portion is composed of at least two additional isotropic lens portions and said lens system has two magnifications that can be determined by a matrix equation.

The terms used in this specification are to be understood as follows:

The term "beside" used in relation to the relative positioning of the first and second lens portions of a dual-refractive lens system refers to the condition that the lens portions are in direct contact with each other on substantially opposite surfaces, i.e., forming a "composite lens" the condition when their opposing surfaces are at a short distance, usually a few millimeters or closer, along their common axis.

The first and second lens portions of a multi-focal non-achromatic dual-refractive lens system for curvature of opposing surfaces

The term "practically coincident or complementary" as used herein means that when these surfaces are in contact with each other, they fit at any point along their boundaries, such as practically identical curves when the surfaces are even planes of infinite radii the surfaces facing each other are completely overlapping. The complementary surfaces are, for example, congruent and convex surfaces, or convex and concave surfaces of equal curvature and radius of curvature.

By "compound lens" is meant a lens system having at least two lens portions, the two opposing lens portions of the adjacent lens portions being substantially identical or complementary, so that the two lens portions can be glued along their opposed surfaces, i.e., planenclavex. The term "compound lens" may also be used to describe a lens system in which the opposed surfaces of the lens portions are spaced apart to be used in one or more optical devices other than the lens, such as a polarizer.

The term "contact lens" refers to a lens system having at least two lens portions, and which lens system substantially meets the requirement that the optical magnification of the lens system be equal to the sum of the optical magnifications of the lens portions.

The term "non-achromatic" is used to refer to a lens or lens system having one or more magnifications that depend on the wavelength of the focused (i.e., used) light that is due to the scattering property of the dual-refractive and / or isotropic optical material used to manufacture the lens or lens system. can be attributed.

The term "achromatic" is used to refer to a lens system having one or more magnifications, at least one of which exhibits a dioptric value that is constant over at least two different wavelengths of focused (i.e., used) light.

In a multi-focal, non-achromatic and achromatic dual-refractive lens system, as described above, a dual-refractive lens portion may be associated with at least one other dual-refractive lens and / or at least one isotropic lens with or without at least two can be preselected, these focuses are along the lens axis of incident light parallel to the lens axis, and that the curvature of either the first or second lens portion can be selected independently of the preselected focuses. Within these constraints, a variety of multi-focal optical designs can be created to meet many practical requirements. For example, within the scope of the invention, a lens system may be provided wherein a dual refractive lens portion is combined with one or more isotropic lens portions to produce a composite lens or series of lenses; a dual refractive lens portion is combined with at least one other double refractive lens portion, either as a composite lens or a series of lenses, optionally with one or more isotropic lens portions, and the like. In addition, as described below, the multi-focus dual refractive lens systems of the present invention may be used in combination with another polarizing device or polarizing filters, which polarizing device or polarizing filters are located between one or more adjacent pairs of dual-refractive lens parts and / or spaced out, allowing you to select one or more magnifications from a plurality of usable magnifications.

The multi-focus, dual-refractive lens system of the present invention allows for a wide range of optical magnifications, which is advantageous in many applications, such as the design of ophthalmic dual focus lenses with relatively large magnification differences with relatively thin lenses and different types of optical instruments. and devices such as telescopes, video and still cameras, or their lenses, microscopes, copiers, optical instruments, spectrographs, etc.

The multi-focus dual refractive lens system of the present invention will be described in detail with reference to exemplary embodiments of the drawings.

Figure 1 is a schematic diagram of an exemplary embodiment of the dual-light refractive lens system of the present invention showing a "perfect geometry" design.

Figure 2 is a schematic diagram of a dual refractive lens portion that can be inserted into a lens system of the present invention.

3A. Fig. 4A is a diagram illustrating a further embodiment of a dual refractive lens system.

3B. Figure 9 is a schematic diagram of another possible embodiment.

Figure 4 is a schematic diagram of another exemplary embodiment of the dual-refractive lens system of the present invention.

Figure 5 is a schematic diagram illustrating a further exemplary embodiment.

Figure 6 illustrates the dual-refractive lens system of the present invention in combination with a polarizing device.

Fig. 7 is a diagram illustrating the dual refractive lens system of Fig. 6, which lens system consists of two dual refractive lens portions showing more than two simultaneous magnifications.

Figure 8 shows the lens system of Figure 7 in combination with a polarizing device.

9A. Fig. 4A is a schematic front view of a spectacle lens incorporating a dual refractive lens system of the present invention.

9B. 9A. Figure 9 is a side view of a spectacle lens.

The following is a description of multi-focal non-achromatic dual light refractive lens systems.

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Each known dual-refractive lens system has an optical axis (i.e., an axis inside the crystalline dual-refractive material) that is perpendicular to the lens axis. Thus, a dual refractive lens system has two specific refractive indices, n ₀ (for simple waves or rays) and n _e (for extraordinary waves or rays), but only in the special case of the e-rays passing in the direction of the double a refractive lens which is perpendicular to the lens axis. When passing in all other directions, the rays have an effective refractive index n _eeff , which is between n ₀ and n _e . In such a case, it is not possible to predict reliably what the optical function or behavior of the dual-refractive lens system will be for the e-rays.

For this reason, it may be desirable to use a dual focus lens system having two independently selectable magnifications (or focuses) where the e-rays pass through the dual refractive lens only perpendicular to the optical axis. The design in which all the e-rays pass through the double refractive lens at right angles to the optical axis is called the "perfect geometry" dual refraction lens design.

Figure 1 shows such a perfect geometry birefringent lens system shows an exemplary embodiment which Ri and _R2 formed in spherical surfaces of radius of curvature of an isotropic (10) of the lens portion and R ₃ and R ₄ formed in spherical surfaces of radius of curvature of an isotropic (30) of the lens portion, which are birefringent and (20) placed before or after the lens portion. The lens portion (20) is bounded by spherical surfaces of radius of curvature R ₂ and R ₃ and the optical axis of the lens portion (20) is indicated by a solid arrow. (The optical axis is indicated by solid arrows in each figure and the direction of incident light by the dashed arrow.) For a perfect geometry dual focus lens system, the pre-selected magnifications D _a and D _b

D34 + D _o + D12 = D is _the equation _for D34 + D _e + θΐ2 ⁼ Db and the "perfect geometry": (Ia) (Lb) 1 (rie - l) x - D [ ₂ (2) wherein D ₁₂ and D ₃₄ of the front or rear portions isotropic lens magnifications, and D _o and D _e of the birefringent lens portion magnifications o-rays and e-rays. The following equations can be used for this perfect geometry design: D _o D _e n ₀ - 1 n _e - 1 (3) or D _e = mxD ₀ (4)

where

The "perfect geometry" dual focus lens system shown in Figure 1 can then be determined by the following equations:

D _a -D _b = - ^ —- x (n ₀ -l) (6a) ** o 'e

D _a -D _b

D _e ---- χ (n _e —1) (6b) n ₀ n _e

D34 ⁼ D;, - D ₀ -D j 2 (7)

For example, by pre-selecting the radius of curvature R _3, the radius of curvature R ₂ can be calculated from equations (6a) or (6b). Then the radius of curvature can be determined, and the preselected radius and the equation (7) of curvature R _3] R ₄ of curvature radius R can be calculated from a radius R ₂ and the equation (2) calculated curvature. In principle, any of the four rays can be preselected.

In a commonly occurring design of a lens system with imperfect geometry, the e-waves pass through the dual-refractive lens in a direction that is not necessarily perpendicular to the optical axis. The e-rays thus have a unique effective refractive index n _{e eff} , which is between n _e and n ₀ . As neither the effective n _{e eff} refractive index or the e-rays path within the birefringent lens is not known in advance, the roads and the actual n _{e ff} refractive indices are mutually interdependent, the lens system comprising a birefringent lens occasional operation n _e values and it cannot be directly estimated or judged on the lens geometry.

A reasonable calculation of the function of dual-refractive lenses can be based on a detailed design of the beam transmission of light rays through the lens. Such beam transmission also includes the determination of the spatial components of the light propagation velocity vectors between an isotropic and a double-light refractive matter, before and after any internal response. For the purpose of selecting or orienting the optical axis of a dual-refractive material, this definition includes the Huygens structure, a general case of a tangent planar structure on your elliptical thorax, such as J in Strong's Concepts of Classical Optics (published by WH Freeman and Company, 1958). Based on such beam-through calculations, which of course are applicable to o-rays, virtually all interesting operating data can be calculated, such as lens magnification, sharpness, and chromatic and spherical aberrations. To determine the transmitted amplitude of the light passing through the interface between two optical materials, the Fresnel formula also makes it possible to determine the transmitted luminance of a multilayer lens.

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Referring to FIGS. 1 to 5, some exemplary embodiments of the non-perfect geometry dual-refractive lens systems of the present invention are described. In these examples or in the following description, the following definitions are used:

DVO The standard rear peak magnification obtained from calculations is the rear peak magnification for o-rays.

DVE The standard rear peak magnification obtained from calculations is the rear peak magnification for e-rays.

DO Beam Peak Calculations for posterior magnification for o-rays.

DE Radius transfer calculations for posterior peak magnification for e-rays.

ACM The "degree of sharpness", that is, the ratio of the minimum focal spot to the surface (i.e., cross-section) of the lens.

PTR Percentage of luminous incident incident light averaged over transmitted light.

n ₀ Refractive index of the dual-beam refractive lens for oscillators.

n _e Refractive index of the dual-refractive lens portion for e-rays when the rays e are perpendicular to the optical axis.

n ₁₂ Refractive index of the isotropic lens portion, which is formed by the radii of curvature R, and R ₂ .

n ₃₄ Refractive index of the isotropic lens portion formed by the radii of curvature R ₃ and R ₄ .

gamma Angle between optical axis and lens axis.

subspace Angle between incident light rays and lens axis.

alfap Angle between the incident light beam and the plane formed by the lens axis and the plane formed by the optical axis of the dual-refractive lens portion and the lens axis.

R 1, R 2, R 3 and R ₄ Figs.

d Lens system diameter.

C ₁₂ , C ₂₃ , and C ₃₄ A 2-5. The thicknesses in the center of the lens systems shown in FIGS.

DF Reverse distance between center of focal spot and lens system (in dioptres).

D _pr Prism magnification in prism dioptres (1 prism diopter = 1 cm beam offset).

The design data of the double-light refraction lens portion (20) shown in Figure 2 is as follows:

Radius of the front face: R ₂ = 7,5 mm

Rear surface radius: R ₃ = 7,8 mm

Thickness of center: C ₂₃ = 0.05 mm

Diameter of lens system: d = 6 mm

Orientation of the optical axis: gamma = 90 ° Refractive indices: n ₀ = 1.443; n _e = 1.8

Direction of incident light: alpha,. = 0 °

Table 1A

Figure 2 shows the data of the double refractive lens portion relative to the o-rays

DVO DO ACM PTR 2.39 2.84 4.8x10 ^-3 93%

Table 1B

Fig. 2 is a view of the portion of the double light refractive lens portion relative to the e-rays

DVE BUT ACM PTR 4.42 5.11 2.85x10 ^-3 79%

The above data show that the actual values of the rear peak magnifications of DO and DE are higher than the corresponding values of DVO and DVE. This incident beam of light beams is due to its non-zero aperture. Indeed, it can be seen that at zero aperture incident light, DO and DVO are exactly the same, and DE and DVE collapse close. In the case of incident light on the axis, the two focal spots are exactly on the lens axis. Note that the sharpness of the e-rays is superior to the sharpness of the o-rays. The transmission losses for the e-rays are greater than the transmission losses for the o-rays because the e-rays differ more than the o-rays.

3A and 3B, the dual-refractive lens portion (20) of FIG. 2 is combined with the isotropic lens portion (10 and 30). The only difference between the two lens systems lies in the position of the optical axis of the dual light refractive lens portion (30). In the embodiment shown in FIG. 3A, the optical axis of the lens portion 30 is perpendicular to the lens axis, and in the embodiment shown in FIG. 3B, it is inclined approximately 60 ° with respect to the lens axis. In both lens systems, the lens parameters are chosen such that the lens systems are practically afocal to the simple rays (i.e., their magnification is zero) and positive to the e-rays. These parameters are:

Radii of curvature: R ₍ = 7,85 mm

R ₂ = 7.5 mm R ₃ = 7.8 mm R ₄ = 7.8 mm

The thickness of the middle: C ₁₂ = 0.04 mm

C ₂₃ = 0.05 mm C ₃₄ = 0.03 mm

Diameter of lens system: d = 6 mm

Refractive index of lens material: n ₁₂ = 1.443 n ₀ = 1.443 n _e = 1, 8 n ₃₄ = 1.443

Direction of incident light: gamma = 90 °

Direction of incident light: subspecies = 0 °

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Table 2A

Figure 3A shows the data for the dual refractive lens portion relative to the o-rays

DVO DO ACM PTR -0.10 -0.10 0.75x10 ^-3 93%

Table 2B

Figure 3A shows data for the dual refractive lens portion relative to the e-rays

DVE BUT ACM PTR 1.93 2.11 7.5x10 ³ 85%

The two focal points of each ray of light incident parallel to the lens axis are located exactly on the lens axis. The transmittance of the e-rays is increased relative to a single dual-refractive lens (Figure 2), but the sharpness is slightly reduced.

The lens system outlined in Figure 3A also describes the operation of off-axis incident light. In Tables 3 and 4, the calculations and their results are shown only to the e-rays because the o-rays behave in a manner that can be determined from known isotropic lenses.

Table 3 shows data for the incident beam of light, in which case the angle between the incident plane and the optical axis of the dual refractive lens portion is zero.

Table 3

Direction of incident light: alpha = 30 °; alpha _p = 0 °

DVE * DF ACM PTR Dpr 1.93 1.93 98x10 ^-3 89% 0.75

* Included with incident light on the axis

From these data, it is apparent that a dual refractive lens system of the present invention has an effective magnification DF which is substantially the same as magnification DVE of incident light on the axis. From a lens construction perspective, such a characteristic may be advantageous, for example, for ophthalmic lenses and contact lenses, where it may be desirable to maintain the same effective magnification regardless of the angle of incident light relative to the lens axis, even if the sharpness of the image is somewhat reduced.

The behavioral data of this lens system are shown in Table 4 for the case where the rays of light fall outside the axis and in which case the optical axis is perpendicular to the incident light plane.

Table 4

Direction of incoming light: alpha,. = 30 °; alpha _p = 90 °

DVE * DF ACM - e-rays PTR ° pr 1.93 2.24 35x10 ^-3 89% 0.74

^x To the incident light on the axis

Comparative studies of this type of incident light show that the dual refractive lens system of the present invention is very similar to an isotropic lens system with the same magnification of DVE. The practical consequence of this is that the conventional optical conditions and properties of a contact lens are practically retained for this type of incident light in the dual-refractive lens system of the present invention.

The combined data in Tables 3 and 4 show that, for a dual-focus contact lens, the reading addition is preferably determined with respect to the e-rays, while the far-sighted complement is preferably determined with the consideration of the o-rays. These data also show that the optical axis of a dual-focus contact lens can be adjusted in a direction that is substantially vertical. The field of vision is then assumed to be horizontal, such as left to right. Conversely, if the field of vision is assumed to be predominantly vertical, the data in Tables 3 and 4 show that the optical axis of the biphasic contact lens can be substantially horizontal.

As described above, only one double-refractive lens portion and one isotropic lens portion are required to obtain two independent preselected magnifications. For special tasks, it may be advantageous to use a system consisting of three or more lens parts. Such a lens system according to the invention is shown in the schematic of Figure 3A. This lens system is a contact lens which can be placed on the peritoneum of the eye, wherein a double refractive lens (20) of the same diameter as the maximum pupil diameter is embedded in an isotropic lens portion having a diameter corresponding to the pupil diameter. The dual-refractive lens portion (20) is preceded by an isotropic lens portion (10), and behind it an isotropic lens portion (30). The lens portions (10 and 30) function as separate lenses, even though they are in reality formed as a single lens. The different parts may be made of the same or different optical materials. For example, a double refractive polymer such as that described in the patents listed above or a directional polymer such as polymethyl methacrylate which is stretched may be used. It may be combined with an isotropic contact lens material such as a hydromethyl methacrylate polymer or a (non-stretched) polymethyl methacrylate. From these, a suitable biphasic contact lens according to the invention can be obtained.

Figure 4 illustrates another dual refractive lens system of the present invention consisting of a dual refractive lens portion (20) and an isotropic lens portion (30). The structural parameters of this lens system are as follows:

Radius: R ₂ - 38 mm

R ₃ = 50 mm R ₄ = -50 mm

Center thickness: C ₂₃ = 0.2 mm

C ₃₄ = 1.0mm

Diameter of lens system: d = 6 mm

HU 208 584 Β

Material of the lens:

Direction of the optical axis: Direction of the incident light:

n ₀ = 1.443 n _e = 1.8 n ₃₄ = 1.443 gamma = 90 ° alpha, = 0 °

Table 5A

Figure 4 shows the data of the double refractive lens portion relative to the o-rays

DVO DO ACM PTR 20.63 20.77 0.007x10 ^-3 93%

Table 5B

Figure 4 shows the data for the dual refractive lens portion relative to the e-rays

DVE BUT ACM PTR 22.96 23.03 0.008x10 ^-3 88%

The foregoing results show that the dual refractive lens system of the present invention can be used as a lens within a dual focal lens.

Figure 3B shows that the dual-refractive lens systems of the present invention are dual-focus even when the optical axis has a direction and position that is different from perpendicular to the lens axis.

Table 6A

Figure 3B is a view of the data of the double refractive lens portion relative to the o-rays

DVO DO ACM PTR -0.10 -0.10 0.75x10 ³ 93%

Table 6B

Figure 3B shows data for the dual refractive lens portion relative to the e-rays

DVE ^XX BUT ACM PTR 1.93 1.80 68x10 ' ³ 85%

Gamma - counting to 90 °.

As shown in the previous calculations, the magnification for the e-rays has decreased. This is due to the fact that the actual refractive indices of n _{e > eff} are less than n _e . The image quality for e-rays is lower than for gamma = 90 °. Therefore, in only a few cases, it may be appropriate to apply an angle other than gamma = 90 ° between the optical axis and the lens axis.

Even at angles other than gamma = 90 °, satisfactory lens operation can be achieved in most cases when the difference is small. Therefore, it is also within the scope of the invention to bend a double-refractive polymeric disk having an optical axis in the plane of the disk, which provides a cylindrical surface whose axis is perpendicular to the then circular optical axis. For example, the radius of a circular surface may be one of the rays of a dual refractive lens. Examination of such lenses shows that it behaves or behaves almost in the same way as a lens having an optical axis perpendicular to the lens axis.

In the exemplary embodiments described above, a dual refractive lens portion is combined with one or two isotropic lens portions to produce two different magnifications, the magnitude of which can be produced completely independently of each other so as to remain a free geometric parameter for the complex lens system. For example, in the case of contact lenses, this free parameter can be used to select the appropriate curvature of the rear surface of the lens system. This result is usually achieved by combining two dual-light refractive lens portions. For the sole purpose of creating two magnifications, the angle between the optical axes of the two dual-refractive lenses must be 90 ° so that o-rays form e-rays in the second double-refractive lens and vice versa. This arrangement, which may be referred to as a "crossed double-refractive" lens system, is illustrated in Figure 5.

The structural parameters of the lens system of the dual-light refraction lens portions (20 and 21) shown in Figure 5 are as follows:

Radius of front face: Radius of intermediate face:

Rear surface radius:

Center Lens Thickness:

Second lens center thickness:

Optical Material Front Lens:

Second lens:

Optical axis direction:

7.9mm 7.5mm 7.8mm

0.06 mm

0.06 mm n ₀ = 1.443; n _e = 1.8 n ₀ = 1.443; n _e = 1.8 gamma, = gamma ₂ = 90 °

Optical axis angle: 90 °

Direction of incident light: alpha,. = 0 °

The value symbols in Table 7 below are as follows:

DOE Magnification for o-rays in the first lens and e-rays in the second lens.

DEO Magnification for the e-rays in the first lens and for the o-rays in the second lens.

DVOEandDVEOA are the appropriate magnifications obtained from standard rear peak magnification calculations.

5Q Table 7

Figure 5 shows the calculated data for a dual light refractive lens system

DVOE DOE DVEO BUT HE 1.60 1.84 -2.66 -2.82

The image sharpness created by the lens system of Figure 5 is approximately the same for incident incident light as for the isotropic dual-refractive lens system of Figure 3A.

HU 208 584 Β

Crossed dual refractive configurations are capable of generating large magnification differences for two right angle polarized outgoing light waves, and they can achieve this with very thin lenses. Accordingly, such designs can be used for contact lenses.

The foregoing exemplary embodiments show that the dual refractive lens system of the present invention is advantageously used as an ophthalmic contact lens or as an intraocular lens which requires at least two different magnifications, one for distant vision and one for reading.

The solutions of the dual refractive lens systems of the present invention may serve as or be incorporated into ophthalmic half glasses. A preferred embodiment of such lenses is illustrated in Figures 9A and 9B, in which the dual-focus dual-refractive lens portion (40) is for example a double-refractive-isotropic lens system for reading and distant vision and a single focus (50) made of material. 9A and 9B, the magnification for the o-rays of the lens portion 40 is the same as the magnification of the lens portion 50. The material of the lens portions (40 and 50) is preferably isotropic and identical, for example polyacrylate, and the double-refractive material of which the double-refractive lens portion (40) is made is stretched polyacrylate. For reading, the light beams incident on the axis are primarily used, i.e., the eye movement is such that it maintains a straight line (more precisely the lens axis) between the text being read and the pupil. Such eye movement generally does not require the head to be moved. The text to be read is usually 40 cm from the read and the width of the printed text is usually 20 cm from left to right. As a result, the lens axis of the eye scans and reads at an angle of about 30 ° when reading horizontally printed texts. The spectacle lens is usually 12 mm in front of the cornea. Therefore, the area of the lens of one half of the glasses that provides the magnification required for reading is not larger than about 1 cm horizontally. In any case, the reading space need not be wider than 2 cm. In the vertical direction, the additional reading space or surface needed for reading should be only 1-1.5 cm. Preferably, the reading portion of the lens is positioned at the bottom of the lens of the glasses, as shown in the exemplary embodiment outlined in Figures 9A and 9B.

The use of a dual-refractive dual-focus lens system as a reading lens part provides significant advantages over conventional dual-stage dual-focus half-glasses lenses, which are single-focal for each portion of half-glasses. While the foregoing considerations regarding the required size of a reading lens portion may be applicable to conventional dual-focus half-glasses lenses, such lenses typically have a significantly larger reading portion. This is mainly due to the fact that such a higher magnification section of the usual half glasses lenses are not sympathetic to the cosmetic aspect.

Birefringent lens systems of the invention create an impression on the other hand, as a focus lens would be, which means that it can not be distinguished látástávolságból the section for reading when the dual light fracture lens is n ₀ refractive index, which is the same távolbalátó lens refractive index of . The present invention provides a portion of the lens which is substantially smaller for reading, while at the same time providing a very large magnification for reading, while allowing a small choice of lens thickness, which allows a significant reduction in the total weight of the spectacle lenses. In addition, the dual refractive lens system of the present invention provides the desired magnifications for both reading and distant viewing. Therefore, the field of vision covers the entire spectacle lens, which is especially important when looking downwards at a distance, such as when looking at objects distant from the vertical. Unlike conventional dual-focus half glasses, unlike the dual-refractive lens system of the present invention, the user's head must be folded forward significantly in order to be able to look over the readable portion of the lens.

As described above, two magnifications of the dual refractive lens system are created by two right-angled polarized light waves. For example, if the magnification of the far field of view belongs to a light wave in a vertical polarization plane and the reading magnification belongs to a light wave in a horizontal polarization plane, sunglasses with significantly polarizing filters can be used to select any of the two magnifications In this way, for example, sunglasses may be provided which have a polarizing filter which produces vertically polarized light for distant vision over a larger portion of the lens of the glasses and a horizontally polarized light in a smaller portion for reading. The magnitude and location of the lens portion for distant vision and the lens portion for reading in the lens system are shown in Figure 9A. With such sunglasses, out-of-focus light from reading magnification is eliminated in far-field magnification and vice versa. There is no loss of luminance when compared to the luminance that can be utilized from standard polarizing sunglasses, i.e. essentially 50% of the incident luminance in each of the two focuses. The physical appearance of the sunglasses is designed to be no different from standard polarizing sunglasses, which is cosmetically beneficial.

If the optical axes of the two dual refractive lenses are not at an angle of 90 °, four different magnifications are generally obtained, since the o and e magnifications of the first lens are combined with the o and e magnifications of the second lens. 5 illustrates the lens system

The two additional magnifications are 0.51 and 0.47 dioptres, which means that the lens is practically three-focus.

FIG. 7 illustrates a dual refractive lens system having two lens portions (20 and 21) having an angle between the optical axes other than 90 °. In general, the four magnifications of a lens system comprising two dual-refractive lens portions are determined by the following equations:

Dlo + θ2ο ⁼ D _a (8a) Walnut + D _2e = D _b (8b) Di _e + D _2o = D _c (8c) Dle + D _2e = D _d (8d)

wherein D _{lo is} the magnification of the first lens at o-rays, D _{le is} the magnification of the first lens at e-rays and so on, and D _a , D _b , D _c and D _{d are} the resulting magnifications of the combinations when the two lenses are in contact.

Magnification of a lens with good approximation (according to J. Strong, p. 319, above refer to page 7 of our description):

D = (nl) xS (9), where D is the magnification, n is the refractive index and S is the so-called "shape factor" of the lens. Equation (9) may also be used if the dual-beam refractive lens is not of perfect geometry (e.g., in Figures 3A, 4 and 5). Considering equation (9), the magnitudes of D _lo and D _{le of the} o-and e-rays of the first lens are:

θΐο "(ηι _ο - l) xS, (10a)

D _le = (n _Ie -l) xS, (20b)

D _le = m, xD _l0 (10c) where and where n _le and n _lo are refractive indices of the first lens in the e- and o-rays, respectively. Similarly, the equations can be applied to the second lens.

In the following, a lens system is provided which has two double-refractive lens portions made of the same dual-refractive material. Taking into account equations (5 '), (10) and (8), the four magnifications of such a lens system are determined by the following equations:

Walnut + _D20 = D _a (If) Walnut + nixD _2o = D _b (11b) mxD _l0 + D _2o = D _c (11c) mxD _lo + mxD ₂ - D _d (IId)

This series of equations shows that the four magnifications cannot be selected independently. Equations (11) allow only two of the four magnifications to be selected in advance. This is true even if the two double-refractive lens portions are made of different double-refractive materials.

If a lens system of Figure 7 has three focuses, then two of the four magnifications should be the same. As can be seen from equations (11), there are only two possibilities which are:

D _a = D _d (12) or

D _b = D _c (13)

In the case where D _a = D _d , then D _l0 =

-D ₂₀ and consequently D _a = D _d = 0. Then three magnifications of this lens system:

D _b = D _lo x (lm) (14) D _a = D _d = 0 (15) D _c = -D _{20 °} x (l - m) (16)

that is, there are equal differences between them. The constant difference between the three enlargements can be selected freely, that is, two of the three enlargements can be freely selected or preselected. The choice of deviation determines D _{) o} or are related. For a given choice of surface of one lens, D _lo determines the surface of the other lens if the two lenses have common or complementary opposing surfaces.

For D _b = D _c , D _l0 = D ₂₀ , and the three magnifications are obtained from the following equations:

D _a = 2xD ₁₀ (17)

D _b = D _c = (m + l) xD _l0 (18)

D _d = 2xmxD _l0 (19)

As can be seen from Equations (17), (18) and (19), the value of one of the three magnifications determines the other two magnifications, so in this particular case there is no possibility of pre-selecting two magnifications independently of each other.

It will be apparent from the foregoing that, by supplementing with an isotropic lens, a series of magnifications can be shifted toward a desired series of values without, of course, altering the differences between each magnification.

If, in a lens system containing two pieces of dual-refractive lens, the dual-refractive lens has some freedom of rotation about the lens axis, then the lens system functions as either four-focus or two-focus lenses when using polarized light enters the lens system. Fig. 8 is a schematic diagram of such a lens system having a polarizing filter (60) and two dual refractive lens portions (20 and 21). As described above, only two of the four usable magnifications can be predetermined independently if the lens system includes two dual-refractive lens portions and not isotropic lens portions. For example, if one of the two dual-refractive lens portions is combined with another isotropic or double-refractive lens portion, the combined lens portion has two independently selectable magnifications D ₁ and D ₂ . Consequently, the resulting four magnifications can be determined by the following equations:

Di + D _2o = F _a (20a) D, + mxD _2o = D _b (20b) D ₂ + D _2o = D _c (20c) D ₂ + mxD _2o = D _d (20d)

Equations (20) show that three of the four magnifications can always be preselected, only one remains, the fourth magnification, which depends on the preselected three magnifications.

HU 208 584 Β

To generalize the previous results, the following statements can be made:

(1) A dual-refractive lens of a given material has two different magnifications at the same time, of which only one of the magnifications can be preselected, the other magnification is a function of the magnitude or extent of the preselected magnification, (2) the lens system of the second dual-refractive lens portion has two magnifications, each of which is preselected independently of the other.

(3) Two systems of dual-refractive lenses generally have four magnifications, two of which can be selected independently, and the other two are dependent on the two selected magnifications.

(4) When two dual refractive lenses are combined with one isotropic or another dual refractive lens, three of the four magnifications can be preselected, with only the fourth magnification being a function of the three preselected or one of them.

(5) It can be seen that in a lens system containing three dual-refractive lenses, only three of the eight magnifications obtained can be pre-selected independently.

(6) When the three dual-refractive lenses are combined with an isotropic or other double-refractive lens, only four of the eight magnifications obtained can be selected to any size.

In general, the number of magnifications N obtained as a result of a lens system containing an M dual-refractive lens can be determined from the following equation (e.g., Eng et al., Cited above, page 2):

N = ^2M (21)

The number of N _free enlargements that can be freely selected:

^ free ⁼ M (22)

If, in a lens system comprising M dual-refractive lens portions, at least one lens portion is combined with an isotropic or other dual-refractive lens portion, the resulting magnification is again N, but the number of _free magnifications N can be determined by the following equation:

N = _No Abad Μ + 1 (23)

The above equations apply to a predetermined M double-refractive material. If one can choose to define the M refractive material M, it is possible to give the desired magnification more than the number of _free magnifications N.

Dual refractive lenses and lens systems offer the opportunity to have different magnifications for different brightness levels. As regards the brightness relative to that first mentioned that of incident natural light is divided vectorially, i.e. the o- and e-rays, waves for the _o and the _e amplitudes Measures of

where A is the amplitude of the incident light. It follows that 50% of the available brightness is directed towards each of the two focuses.

As a result of the above, the ratio of focused to out-of-focus light, or luminance in both focuses, is 1: 1. This is extremely advantageous when compared to other known dual focus lens solutions and the results obtained with these.

This ratio can be adjusted to any desired degree when linearly polarized light enters the lens system comprising at least one dual-refractive lens. Fig. 6 is a schematic diagram of a dual refractive lens system in which the relative orientation of the optical axis of the dual refractive lens portion relative to the vibration plane of the incident polarized light is represented by the beta angle. The polarized light (80) is produced by a polarizing device. The luminous intensities I _o and I _{e for} the _o and e rays can be obtained from the following equations:

I _o = I _p sin ² beta (25a)

I _e = Ip cos ² beta (25b) where I _{p is} the luminance of the incident polarized light. It follows from the equations (25) to the ratio I _o and I _e can be made from any mértékűvé appropriate choice of angle beta. If a standard polarizing filter is used to produce polarized light, this ratio selection can be achieved at the expense of loss of total luminance. However, in some applications, it may be important to reduce the brightness of the out-of-focus light at one of the magnifications rather than to have a higher, but equal, brightness at both magnifications. In some applications, it is possible to use a high light transmission polarizer such as that described in U.S. Patent 3,552,985, in which case the surface luminance is substantially unaffected.

The above embodiments are essentially dual refractive dual focus lens systems comprising, for example, two reciprocal lens portions (FIG. 5), or lens systems having a dual refractive and one or more isotropic lens portions of Figures 3A, 3B and 4.

The luminous intensities for the four magnifications of the dual light refraction lens system of Figure 7 can be obtained from the following equations:

1 (00) = (I / 2) xcos ² beta ₁₂ (26a)

I (OE) = (I / 2) xsin ² beta ₁₂ (26b)

I (EO) = (I / 2) xsin ² beta ₁₂ (26c)

I (EE) = (I / 2) xcos ² beta ₁₂ (26d) where 1 (00) is the luminous intensity for the o-rays in the first dual-refractive lens and the o-rays for the second double-refractive lens and so on; and I is the angle between the luminous intensity of the incident non-polarized light and beta _{12 is} the angle between the optical axis of the two dual-light refractive lens portions. Equations (26) show that light at different magnifications13

EN 208 584 Β certain degree of freedom of choice. For example, if the lens system is designed for three focuses with the same brightness for each of the three magnifications, then for _D10 = _-D20 , the beta angle ₁₂ can be determined from the following equations:

I (00) + I (EE) = I (OE) = I (EO) (27) or cos ² beta2 = (sin ² beta12) / 2 (27 ') resulting in a beta, ₂ = 54.7 ° (28 )

Alternatively, when D _lo = D _20, the angle between the two optical axes must be beta ₁₂ = 35.3 ° (29).

Using a polarizing filter on the front of a lens system comprising two dual-refractive lens portions and optionally one or more isotopic lens portions, as shown in Figure 8, the resulting luminances of the four magnifications obtained can be determined from the following equations:

I (CO) = (I / 2) xsin ² betaxcos ² beta ₁₂ (30a)

I (OE) = (I / 2) xsin ² betaxsin ² beta ₁₂ (30b)

I (EO) = (I / 2) xcos ² betaxsin ² beta ₁₂ (30c)

I (EE) = (I / 2) xcos ² betaxcos ² beta ₁₂ (30d)

Equations (30) show that the lens system outlined in FIG. 8 can be made single-focus, bi-focus, or quad-focus when dual-refractive lenses are made with a degree of freedom of rotation around the lens axis.

The following describes multi-focus dual refractive lens systems that are achromatic or exhibit a predetermined degree of chromatic aberration.

The multi-focal lens systems of the present invention, having one or more dual light refraction and containing one or more isotropic lens portions, may also vary in achromaticity. The following considerations regarding the achromaticization of lens systems are comparable to those discussed, for example, by M. Herzberger in The Handbook of Physics (McGraw-Hill, 1967, p. 6-42). Herzberger's treatment of achromaticism differs somewhat from the much more general theory used, for example, in J. Strong, p. . Note that in the following description of the achromatic dual-refractive lens system, the term "co-located" with respect to the relative position of each component is used as described above, but non-achromatic lens systems, i.e., 1, 3A, 3B and 4-9. . The above described lens systems differ from the achromatic lens systems in that the latter do not require two opposed lens surfaces of the same or complementary curvature.

A system of lenses with a single refractive lens portion and at least one isotropic lens portion with either perfect or imperfect geometry at both preselected magnifications is achromatic if the following equations can be solved (the most which includes the perfect geometry):

D ,, _bl + D _2obl + D ₃ , bl ⁼ D _a , _b i (31a) Di, _r + D _2or + D _3r = D _ar (31b) D ,, bi + D _2e , bi + θ ₃ , Μ = D _bbl (31c) θΙ, Γ + D _2e , _r + D ₃ r = D _br (31d) with the condition that D _a , bl ⁼ D _a , r “D _a (32) and Db.bl ⁼ D _b , _r = Db (33)

In equation (31-33), D _{lbl is used} to _enlarge the isotropic lenses "1" to blue light ("bl"), D _2ob to enlarge the "2" double light refractive lens to o-rays and blue light ("bl"), D _3r refers to the magnification of the isotropic lens to red light ("r") and so on.

Note that the indices "bl" and "r" merely mean that they refer to two different wavelengths and that the following description is not limited to blue and red light, that is to say, to these two selected wavelengths.

In the following, we take into account that the shape factor of a lens, denoted by the letter S, is a good approximation of the following equation:

S = - ^ - (9 ') η- 1 where D is the magnification of the lens and n is the refractive index of this magnification. For the sake of simplicity, η - 1 is then denoted as n', that is, η '= η - 1, for example, the magnifications D _3bl and D _3r can be related to the following equation:

If the lens system of Equation (31) is to be achromatic at both magnifications, then the following conditions must be satisfied:

D ₂ o, bl ~ ü _2e , bl ⁼ θ 2ο, Γ ^- D _2e , r (35) which results in the limitation:

ⁿ 2o, bl ^{_ n} 2e, bl ' ⁿ 2o, r ⁿ 2e, r (36)

The difference between refractive indices for e- and o-waves is called the "double refraction" of matter. Consequently, a lens system comprising a dual refractive lens portion and at least one isotropic lens portion can be made achromatic at both preselected magnifications in both imperfect and perfect geometry embodiments when the dual refraction lens portion has two " r "as described above.

HU 208 584 Β

A lens system capable of producing two preselected magnifications with a dual light refractive lens and two isotropic lenses can generally be made achromatic in one of the two preselected magnifications. For example, a lens system is described in which the magnification corresponding to the e-rays is achromatic. Then the following series of equations must be satisfied or solved:

D ,, bi + Ye, bi ⁺ Y.bi = D _a bi (37a)

Dl, _r + ^ 2e, r + Y, r ⁼ Yr (37b)

Y, bl + ^ 2o, bl ⁺ Y.bl = D _bbl (37c)

Due to Equations (9 ') and (34), this sequence of equations is transformed as follows:

1 ⁿ '2e, bl 1 Y.bl Y.bl ⁿ 2o, bl n'i, r n'2e, _r 1 X ^D 2o, bl = ^D a, r ⁿ I, bl ⁿ 2o, bl 1 1 1 13> 3, bl Y.bl

The following requirement must be met for an achromatic lens:

D _{a> b} i = D _a , _r (39)

D _{a bl} and D _{ar may} have different preselected values if the lens may exhibit some chromatic aberration or color defect at this magnification.

Equation (38) equals Ü! solvable _bl, D _{2obl bl} and D ₃ data knowledge, equation (34), taking into account any magnification.

At a given magnification, a lens retains a degree of freedom in the lens geometry. Consequently, the three lenses in contact with each other have three degrees of freedom, a composite lens formed by two common surfaces exhibits two degrees of freedom when contacted with a third lens, and a complex lens having three degrees of freedom has another degree of freedom for such a lens system geometry.

If the requirement for the lens system of equation (38) to exhibit achromaticity and perfect geometry in one of the preselected magnifications is achieved in the following different ways:

(1) The double-refractive lens portion may be positioned at the front so that the light first falls on it and the front surface of the double-refractive lens is flat.

(2) The lens system geometry is limited by the following equation:

D 1 = -D _{2e fs} (40) where D _{2c fs is} the surface magnification of the front surface of the dual-refractive lens adjacent to the first isotropic lens and D is the magnification of the first lens. D, and D _{2efs correspond to} all visible wavelengths.

(3) If there are two isotropic lens portions in front of a double refraction composite lens,

D, + D ₃ = -D _2e , _fs (41), in which D _{3 is} the magnification of the other isotropic lenses.

Strictly speaking, perfect geometry is created for wavelengths "bl" and "r" only in equation (1), and for wavelengths selected in equations (40) and (41) only equation (2) and (3) produce perfect geometry . However, due to the generally moderate wavelength dependence of the refractive index of isotropic and double-refractive materials, the limiting effect of Equations (2) and (3) results in geometries that are substantially perfect.

The following is a description of the achromatic dual-refraction lens systems at two preselected magnifications.

In the case of a lens system with two intersecting double-light refractive elements but without an isotropic lens part, the following series of equations shall be solved:

lo, bl ⁺ ^ 2e, bl „θβ, ϋΐ (42a) lo, r ^ 2e, r ~ ^ a, r (42b) le, bl ⁺ ^ 2o, bl ~ ^ b.bl (42c) le.r ^ 2o, r ~ ^ b, r (42d)

under achromatic conditions:

Y.bl ~ Yr ⁼ Ybl ^_ Yr 'θ (43)

Equations (42) and (43) can be solved provided that the following conditions apply:

( ^B lo, r ^{- R} le, r) ^- (^ 2o, r ^- ^ 2e, r) ~ ( ⁿ lo, bl ' ⁿ le, bi)' ( ⁿ 2o, bl ~ ⁿ 2e, bl) (44)

Consequently, the difference between the double refraction of the two lenses must be equal to the two wavelengths considered. This again entails some limitations in the choice of double refractive material.

Finally, a lens system comprising two intersecting dual refractive lens portions and two isotropic lens portions is described. If such a lens system has to be achromatic at both preselected magnifications, then it is possible to solve the following series of equations:

Ybl + Yo.bl + I ^ 3e, bJ + Y, bl ~ Y, bl (45a) Yr + Yo, r + Ye.r + Y, r ⁼ Yi.r (45b)

Cl, b. + Ye.bl + Yo.bl ⁺ Y, bl ⁼ Y, bl (45c) Di, _r + D _2er + D _{3o> r} + D _4r = D _ar (45d) which can be converted as follows:

HU 208 584 Β ⁿ '3o, bl

Π l, r ti 2o, r ti _3er ⁿ 'l, bl ⁿ ' 2o, bl ⁿ ' _3obl tt 2o, bl tt l, r ti 2e, r ti _{3o r} ⁿ ' i, bi ⁿ ' _2ob! n ' _3ob ,

If the two preselected magnifications must be achromatic, Equation (43) must also be valid.

Generally, equation (46) can be solved, but only for two different double-refractive materials.

As already described, a given magnification lens has a degree of freedom. If the four lenses of equation (46) are connected but not assembled, a maximum of four degrees of freedom are available for design and editing purposes. These degrees of freedom can be used to produce perfect geometry lens systems.

For example, if it is desirable to provide the first dual-refractive lens portion with virtually a right angle to all the e-rays on the optical axis, then this lens portion should be positioned behind an isotropic lens portion. Then the magnification D _{b of} the isotropic lens portion satisfies a

Di = -D _2efs (47), in which D ^ is the front surface magnification of the first dual refractive lens for a visible wavelength.

If both the e-rays in the first dual-refractive lens portion and the e-rays in the second double-refractive lens portion are to be perpendicular to the corresponding optical axis, the front surface of the two double-refractive lens portions must be constructed so that the equation (47) the

Di + D ₂₀ = -D _3efs (48). D _{3e fs is} the magnification of the front surface to the e-rays and a visible light, wavelength, at the second dual-refractive lens portion. Since only two degrees of freedom are required to satisfy equations (47) and (48), and since four degrees of freedom are available, the present invention provides a lens system having independently selectable two achromatic magnifications and perfect geometry within each of the dual refractive lens portions.

It will be appreciated that in the case of high refractive index portions, the direction dependence of the refractive index for the e-rays inside the dual refractive index portion is more important than the dependence of the refractive index on the wavelength. Consequently, a perfect geometry design can be important for the construction of achromatic multi-focus dual-refractive lens systems.

X Di.bi D2, bl D3o, bl II D _a , _bl Da, r ^D b, bl ^D 4, bl Pieces, r - - -

If the two double-light refractive lens portions are not intersected, i.e., if the angle between the two optical axes is not 90 ° or 0 °, then there are essentially four magnifications of this lens system. Because o-rays in a dual-refractive lens are comparable to simple rays of light in an isotropic lens, the concept of perfect geometry for o-rays is irrelevant. Therefore, the magnification for the o-rays in both the first and second dual-refractive lenses is achromatic, regardless of whether the lens system meets the constraints of perfect geometry that come with e-rays. Consequently, the magnifications for the respective o- and o-rays, o- and e-rays, and e- and o-rays in the first and second dual-refractive lenses meet the strict achromatic and / or perfect geometric constraints, only the first double-refractive the combination of magnification of the e-rays in the lens and the e-rays in the second dual-refractive lens does not require perfect geometry. Since three of the resulting four enlargements are preselected, it is preferable to pre-select the o-ο-, o-e- and e-o magnifications.

Throughout the preceding description, it is assumed that the incident light consists of parallel rays of light. If one of the described lens systems is to be used for non-zero-bending light, a light-dimming lens can be placed in front of the lens system to convert non-zero-bending light to zero-bending light. This photoconductive lens may be a known or conventional achromatic lens. Calculating the preselection of usable magnifications of a lens system having one or more additional isotropic lens portions in the lens system can be performed in the same manner as described for parallel incident light, using conventional optical methods.

In performing the calculations, it is generally possible to replace any number of j> 2 consecutive isotropic lenses by two isotropic lenses of magnification D _x and D _y , i.e.

Ci, bi + D ₂ bi + .... D _Jjbl = D _{x bl} + D _{y bl} (49a)

Di, _r + D _{2 r} + .... Dj _r = D _xr + Dy _r (49b)

These equations can be solved for D _x and D _y .

It follows from the foregoing that a polarizing device is in motion16

The use of a dual refractive lens portion and a degree of freedom of rotation of the polarizing device about the lens axis converts the lens system of the present invention to a variable achromatic magnification lens system.

All of the considerations discussed above regarding non-achromatic lenses and lens systems are valid and applicable to achromatic lenses and lens systems.

Combinations of the lens systems of the present invention, either achromatic or non-achromatic, enable the production of high-performance optical devices and structures. The acromates, as well as the sum, are also achromatic, so various magnifiers are capable of producing single or multiple magnifications achromatically when using achromatic lens systems in combination with other achromatic lens systems. Various magnifications can be selected by properly rotating the polarizing device and / or by rotating the dual refractive lens portion or lens system.

In addition, two or more dual-refractive lens systems, either achromatic or non-achromatic, can be combined in a system in which one or more of the lens systems can be movable along the axis of the lens system, and have the same degree of freedom. Such a combined system can be used as a variable magnification device as is known in the optical field. The additional degrees of freedom to rotate the dual-refractive lens parts and / or polarizing devices provide additional degrees of freedom to select the desired magnifications.

The foregoing notes are merely intended to indicate the wide range of applications of the lens systems of the present invention, such as cameras, telescopes, microscopes, photocopiers, optical instruments and apparatus, robots, and the like.

The invention has been described above in connection with some exemplary embodiments thereof, which are also illustrated in the drawings, but of course the invention is not limited to these described embodiments. Of course, in the embodiments described, one skilled in the art can make various changes and modifications without departing from the spirit or characteristics of the invention.

Claims (12)

A multi-focus, non-achromatic dual light refractive lens system comprising a lens axis and comprising at least two lens parts, wherein: the first lens portion (20) being a double refractive anisotropic medium lens having an optical axis perpendicular to the geometric axis of the lens portion (20) and having refractive properties for both light waves incident on the anisotropic medium, the first lens portion (20) have separate surfaces of a radius of curvature _{(R2, R3)} - the second lens portion (10, 30) disposed relative to the first lens portion (20) and having an optical axis different from the geometric axis of the first lens portion (20) and having refractive properties on both incoming light waves, i.e., for the ordinary and extraordinary light-wave, said second lens portion (10, 30) are different surfaces of a radius of curvature _{(R3, R4),} wherein adjacent the first lens portion (10) of the surface of the second lens portion (10, 30) of curvature the radius _(R3) and the radius of curvature of the first lens portion (20) adjoining surface mating the second lens portion (10, 30) (R ₃₎ complementary to (complementary to each other), and the second lens portion (10, 30) or a birefringent or an isotropic lens, characterized in that the first lens of the optical axis of the second dual-refractive lens portion (10, 30) a direction (20) other than the optical axis; or the optical refractive index of the second lens portion (10, 30) for two types of light waves, such as normal and extraordinary light waves, is different from the optical refractive index of the first lens portion (20); or the refractive index of normal light waves of the second lens portion (10, 30) is the same as the refractive index of normal light waves of the first lens portion (20), but the refractive index of extraordinary light waves of the second lens portion (10, 30) light waves; or the refractive index of the second lens portion (10, 30) for the extreme light wave is the same as the refractive index of the first lens portion (20) for the extreme light wave, but in this case the refractive index of the second lens portion (10, 30) the refractive index of the lens (20) relative to normal light waves, the lens system further being configured such that the lens system has at least two focuses simultaneously on a predetermined or negative point of the axis of the lens for incoming light rays parallel to the axis of the lens, and that at least one of the radii of curvature (R _b R ₂ , R ₃ , R ₄ ) of adjacent or non-adjacent surfaces of the first lens portion (20) or the second lens portion (10,30) is (R _h R ₂ , R ₃₎ , R ₄ ) is the value of said k value is independent of focus. Lens system according to claim 1, characterized in that it has at least one first lens part (20) or a second lens part (10, 30) which has a first lens part (20) or a second lens part in the path of the light wave. (10, 30) perpendicular to its optical axis. The lens system according to claim 1, characterized in that one of the lens parts (10, 20, 30) 584 Β or more double-refractive lens portions (10, 20, 30) of double-refractive polymer. Lens system according to claim 1, characterized in that the second lens part (10, 30) comprises at least one double light refractive lens part. The lens system of claim 1, wherein the second lens portion (10, 30) comprises at least one isotropic lens portion. The lens system of claim 1, characterized in that it comprises a polarizing device, wherein at least one polarizing filter (80, 90) or only one or two polarized lens portions (20, 21) are axially in the same axis; the refractive lens (20, 21) is located on the side facing the incident light. 7. A multi-focus dual-refractive lens system having at least one focal chromatic aberration or at least one degree of chromatic aberration, and wherein the lens system comprises a lens axis; where - the first lens portion (20) is a dual refractive anisotropic medium lens having an optical axis perpendicular to the geometric axis of the lens portion (20) and having refractive properties for both light waves incident on the anisotropic medium, i.e. normal and abnormal light; - a second lens portion (10, 30) disposed relative to the first lens portion (20), the optical axis of the lens portion (10,30) being different from the geometric axis of the first lens portion (20); which lens portion (10,30) is refractive in respect of both incident light waves, i.e., normal and extraordinary light waves; and the second lens portion (10, 30) being a double-light refractive or an isotropic lens, characterized in that the optical axis of the second double-refractive lens portion (10,30) is different from the optical axis of the first lens portion (20); or the optical refractive index of the second lens portion (10, 30) for the two types of light waves as ordinary and extraordinary light waves is different from the optical refractive index of the first lens portion (20), i.e., the normal and the extra light waves; 10, 30) has the same refractive index for the first light portion as for the extra light waves of the first lens portion (20), but in this case the refractive index for the extra light portion of the second lens portion (10, 30) is different from or the refractive index of the second lens portion (10,30) for extreme light waves is the same as the refractive index of the first lens portion (20) for extreme light waves, but the second lens portion (10,30) has a refractive index for ordinary light waves other than the first refractive index (20) of the first refractive lens (20), the lens system is further configured such that, for incident rays of light incident parallel to the lens axis, the lens system simultaneously has at least two focal points on each axis, or at a negative focal length, and the focal length of at least one of the two focuses is substantially the same with respect to two focused wavelengths of different wavelengths. Lens system according to claim 7, characterized in that it has at least one first lens part (20) or a second lens part (10, 30) which has the first lens part (20) or the second lens part in the path of the light wave. (10, 30) perpendicular to its optical axis. The lens system of claim 7, wherein the second lens part (20) has the same dual refractive properties for two different wavelengths. The lens system of claim 7, wherein the second lens portion (20) is composed of at least two further isotropic lens portions (10, 30) and said lens system has two magnifications (D _a and D _b ) and the following matrix equation is valid: 1 n'u n'2e, bl ⁿ * 2o, bl Π 2e, r 1 1 X ^D I, bl D _2o , bl Da.bl Da r ⁿ l, bl ⁿ 2o, bl 1 1 1 T ^ 3, bl Db.bi wherein n'2e, bi = n ^ .bi -1, ^the optical refractive index of ^the extraordinary light wave on the first lens portion (20) for violet light; n _'2o, bi = _2obl n - 1, where n _2obl the ordinary optical light wave (20) has a refractive index in the first lens portion (20) of a violet light; n'i _r = Π] _r - 1, wherein the optical refractive index of the first isotropic lens portion (10, 30) is red light; ⁿ 'i, ⁿ i ⁼ bi, bi ^_ 1, ^h ° ⁿ l i, bi for ^the first isotropic lens portion (10, 30) of the optical refractive index of red light; n ' _2er = ⁿ 2e, r ^- L where ⁿ 2e, r is ^the optical refractive index of ^the extraordinary light wave at the first lens portion (20) for red light; Dj _bl is a magnification of the first isotropic lens portion (20) under violet light; D _{2obl magnification of} the normal light _{wave of} the first dual light _{refractive lens} portion (20) for violet light bi magnification of the second isotropic lens portion (10, 30) for violet light D _a , bi and D _ar individually selected magnification for violet and red light; Db.bl preselected magnification for violet light, The lens system of claim 7, wherein the at least two double-refractive lens portions (20, 31) are composed of at least two further isotropic lens portions (10, 30) and said lens system has two magnifications, D _a and D _b . , to which the following matrix equation applies: HU 208 584 Β ⁿ 3o, bl rc i, r rc 2ο ₄ rc _3er rc i, bi rc 2o, bi rc _3o , bi ⁿ '2o, bl ⁿ ' and rc ' _2e , r rc' _3or rc'l.bl ⁿ '2o, bl ⁿ ' _3obl where n ' _2or = ⁿ 2o, r' b where ⁿ 2 ₀ , r is ^the optical refractive index of ^the first dual-refractive lens portion (20, 21) for a regular light wave in the case of red light ⁿ '3e, bi ^{= n} 3e, bi - b where n3e, _{bI is} the optical refractive index of the second dual-beam refractive unit with respect to the ultraviolet light wave at violet light; ⁿ '3o, bi ^{= n} 30o, bi ~ b where n 3obl is the optical refractive index of the second dual-refractive lens portion in the case of violet-colored light; ⁿ ' ₃ e, r ^{= n} 3e, r ^_ b where n ^,. the second birefringent optical lens portion has a refractive index for the extraordinary light waves of red color light n _'3o, r _{3 OR} = n - 1, where n is _{3 OR} for normal red light waves of the second double fracture annular light optical refractive index of colored light; n ' _4r = ⁿ 44 ~ b where n4 ra is the optical refractive index of the second isotropic _{lens part in} red light ⁿ ' 4, bi ^{= n} 4, bi ~ b where n _{4bl is} the optical refractive index of the second isotropic _{lens part} in violet light D ₄ , bl a magnifying a second isotropic lens portion for violet light; D _br and D _{b bl} individually preselected magnification for violet and red light; D _ar and D _are each preselected magnification _{of bl in} violet and red light; optical refractive index of lens part for extreme light wave at violet color; n ' _2obI = _{n2o b1} - 1, where _{n2o bI is} the optical refractive index of the first dual-refractive _{lens portion in} the case of violet-colored light; ⁿ 'i, ⁿ i = r, r - 1, ^where NLR in the first sub-lens optical isotropic refractive index of a red light; rc'i.bi ^{= n} i, bi 'b where nl bl is the optical refractive index of the first isotropic lens part in violet light; n'2er = ⁿ 2e, r - b where n2er is the optical refractive index of the first dual-refractive lens portion in the case of an extraordinary light wave in the case of red light; D [ _b] magnification of the first isotropic lens portion in violet light; D _{2obl magnification of} the first dual-refractive lens portion to a regular light wave for violet light; and finally D _{3o bl is} the magnification of the second dual-beam refraction lens portion into a regular light wave for violet light. The lens system of claim 7, characterized in that it comprises a polarizing device, wherein at least one polarizing filter (80, 90) or only one or two polarized lens portions (20, 21) are axially in the same axis; the refractive lens (20, 21) is located on the side facing the incident light.